A. G. Mirochnik

Crystal structure and excimer fluorescence of dibenzoylmethanatoboron difluoride

Fluorescence properties of dilute and concentrated solutions of dibenzoylmethanatoboron difluoride and its crystals were studied. Excimers are formed in concentrated solutions and crystals of dibenzoylmethanatoboron difluoride. The crystal structure of dibenzoylmethanatoboron difluoride was determined by X-ray diffraction analysis. It was found that the molecules of dibenzoylmethanatoboron difluoride are coplanar with an interplanar distance of 3.6 Å.

Fluorescence and photochemical properties of crystalline boron difluorides β-diketonato

The fluorescence and photochemical properties of crystalline β-diketonatoboron difluorides (DBD) RCOCHCOR1BF2 were studied. These compounds are characterized by relatively high photochemical stability. The introduction of electron-donating groups into the aromatic α-substituent of the chelate ring increases and the introduction of electron-withdrawing groups decreases the fluorescence intensity of DBD. Anisoylbenzoylmethanotoboron difluoride was found to exhibit the highest fluorescence intensity. The substituents were shown to influence the relative arrangement of singlet and triplet ηπ* and ππ* levels and luminescence properties of compounds.

Crystal Structure and Luminescence of the [Eu(Phen)2(NO3)3] Complex. The Role of the Ion-Coactivator

The [Eu(Phen)2(NO3)3] complex was synthesized via reaction of europium nitrate with 1,10-phenanthroline (Phen) and studied by X-ray diffraction analysis. The crystals are monoclinic: a= 11.168(1), b= 17.976(2), c= 13.053(1) Å, β = 100.577(2)°, space group C2/c, Z= 4, ρ(calcd) = 1.801 g/cm3. The central europium atom coordinates (on a two-fold axis) six oxygen atoms of three nitrate groups with distances of 2.499(2), 2.502(2), and 2.542(2) Å and four nitrogen atoms of two phenanthroline molecules with distances of 2.542(2) and 2.593(2) Å. The influence of ion-coactivators on the luminescence of Eu3+in the [EuxM1 - x(Phen)2(NO3)3] complexes (M = Y, La, Nd, and Lu) is discussed.

Excimer formation of dibenzoylmethanatoboron difluoride during photolysis in polymer films

ABSTRACT Photochemical behavior of polyethylene, polystyrene and polymethylmethacrylate films containing dibenzoylmethanatoboron difluoride was investigated. It was observed that during UV irradiation of polyethylene films the monomer fluorescence of the complex (λ max=450 nm) transforms into excimer fluorescence (λ max=535 nm).

Europium(III) Acrylatodibenzoylmethanate: Synthesis, Spectroscopy (IR, Luminescence), and Polymerization Properties

Eu(III) acrylatodibenzoylmethanate was synthesized with the aim of obtaining luminescent macromolecular Ln(III) complexes with chromophores. It was homo- and copolymerized with methyl methacrylate. The compounds formed were characterized by elemental analysis, luminescence, and IR spectroscopy. The luminescence intensity of the macromolecular Eu(III) complexes containing dibenzoylmethanate ions was shown to exceed the intensity of the monomeric complex by several times. The increase in the luminescence intensity when going from the monomer to copolymers is explained by the weakening of the quenching effect of the low state of the metal–ligand charge transfer.

Influence of the Nature of Carboxylic Acid on the Luminescence and Spectral Properties of (Carboxylato)bis(dibenzoylmethanato)europium(III) Complexes

A series of (carboxylato)bis(dibenzoylmethanato)europium(III) complexes containing anions of both saturated and unsaturated carboxylic acids were synthesized to compare the luminescence and spectral properties of heteroligand Eu(III) complexes. (Carboxylato)bis(dibenzoylmethanato)europium(III) complexes with unsaturated acid anions were synthesized for the first time. The compounds obtained were characterized using elemental analysis and luminescence and IR spectroscopy. These studies revealed two types of influence of the nature of an acid substituent on the luminescence spectra of (carboxylato)bis(dibenzoylmethanato)europium(III) complexes. The anomalous Stark structure of the luminescence spectra of one group of compounds is attributed to the charge transfer state at 77 K.

Fluorescent properties of europium(III) complexes with polyacrylic acid containing graftedo-phenanthroline groups

Fluorescent properties of EuIII complexes with polyacrylic acid containing graftedo-phenanthroline groups were studied. The presence ofo-phenanthroline groups (2%) in the macromolecular ligand provides a 2- to 3-fold increase in the fluorescence intensity as compared to that for EuIII polyacrylates. The effect of concentration quenching of fluorescence, which is observed as the temperature decreases from 300 to 77 K, is explained by the shortening of the average Eu-Eu distances and by the increase in the efficiency of energy redistribution in the complex.

Fluorescence and Photochemical Properties of Eu(III) Poly(acrylic Acid-co-Ethyl methacrylate) Complexes

Abstract The fluorescent and photochemical properties of Eu(III) with copolymers of acrylic acid and ethyl methacrylate were investigated. It was found that photochemical behavior of Eu3+ complexes with copolymers is essentially different from that Eu3+ complexes with polyacrylic acid-in the former Eu3+ luminescence intensity during photolysis noticeably enhances rather than reduces. Two factors were supposed to cause the enhancement of Eu(III) luminescence efficiency during photolysis: one is responsible for decrease in the efficiency of the energy transfer from Eu3+ to -OH vibrational manifold and the other causes an increase in asymmetric binding site for Eu3+ ions.

RISE OF PHOTOLUMINESCENCE IN THE PHOTOLYSIS OF EUIII COMPLEXES WITH COPOLYMERS OF ACRYLIC ACID AND BUTYL METHACRYLATE

The luminescence and photochemical properties of EuIII complexes with copolymers of acrylic acid and butyl methacrylate have been studied by luminescence, IR spectroscopy, and EXAFS.

Enhancement of Luminescence in the Photolysis Of Eu(III) Poly(Acrylic Acid-co-Butyl Methacrylate) Complexes

Abstract The fluorescent and photochemical properties of Eu (III) with copolymers of acrylic acid and butyl methacrylate were investigated. It was found that photochemical behavior of Eu3+ complexes with copolymers is essentially different from those of Eu3 with polyacrylic acid - in the former Eu3 luminescence intensity during photolysis noticeably enhances rather than reduces. It has been found that the presence of steric hindrances and coordinatively unsaturated structures in the initial complexes with copolymer and peculiarities of the photodecomposition of macromolecular ligand favors the enhancement of the luminescence during the photolysis